Thyroid hormone autoantibodies in a case of Hashimoto's disease

Abstract

A case of Hashimoto's disease is reported. The serum contained antibodies binding T₃ and T₄. The binding capacity and affinity constants for T₃ were 0.03 μmol/l and 3.4 × 10⁹ l/mol and for T₄ 0.3 μmol/l and 1.4 × 109 l/mol, respectively. After total thyroid lobectomy on the left and subtotal on the right the autoantibodies disappeared from the serum. Thyroid tissue from the patient proved to contain an antithyroglobulin. According to the findings, the T₃-and T₄-binding antibodies are directed against thyroglobulin. It is of clinical importance to bear these autoantibodies in mind as possible errors in measuring T3 and T4 by radioimmunoassay (RIA). If RIA determination gives unexpectedly high or low T₃ and/or T₄ values, testing of non-specific binding is recommended.

Key Words:

• antithyroglobulin
• Hashimoto's disease
• lymphomatous thyroiditis
• radioimmunoassay
• thyroid hormone